In Europe, two drugs will compete to treat rare blood cancer

In Europe, two Bay Area pharmaceutical companies will go head-to-head over new drugs that both treat a rare blood cancer, chronic lymphocytic leukemia, in patients whose disease has returned.

Last week, Gilead Sciences of Foster City won federal approval for Zydelig, its first cancer drug. It’s playing catch-up with Imbruvica, which is sold by Pharmacyclics of Sunnyvale as well as Johnson & Johnson. That drug won approval in February for patients who’d previously been treated for chronic lymphocytic leukemia. On Monday, the drug was also approved to treat the disease in patients with a certain genetic mutation, whether they’ve previously been treated or not.

While Imbruvica has a head start on capturing market share in the United States, it may well compete with Zydelig at the same time in Europe. On Friday, the European Medicines Agency recommended the use of both drugs.

The two drugs aren’t exactly the same. In addition to chronic lymphocytic leukemia, Imbruvica can treat mantle cell lymphoma, another rare and aggressive type of blood cancer. Zydelig can also treat relapsed follicular B-cell non-Hodgkin lymphoma and small lymphocytic lymphoma. There’s also a price difference: in the United States, Zydelig costs $7,200 a month, compared with Imbruvica at $8,200 a month. (Zydelig has more serious risks, including potentially fatal liver problems.)

Overall, the drugs treat cancers that affect a type of white blood cell called B-lymphocytes, or B cells. In these cancers, lymphocytes grow too fast and live too long, so there are too many in the blood or in the lymph nodes.

The National Cancer Institute estimates that 15,720 Americans will be diagnosed with, and 4,600 will die from, chronic lymphocytic leukemia this year.